Its been a few months since we had a robot to program so Im shakin off the cob webs a little still. I had an idea for this one but I cant seem to figure out how to get it to work. Im hoping dome crowd sourcing will help.
The cell we're building is pretty simple, the robot is mounted inverted on the front of an existing machine and will simply pick sheets of plastic to be formed and load them then unload the finished part and put it on a conveyor. As the robot repeats this process the stack of material will get lower and lower. In the past we have had customers install vision systems to detect how close the tool is to the part (sadly, they had a different company do this so I didn't get a chance to be involved with that setup) but this isn't in the budget for this project. I have also set up a "reverse palletizing" system in the past that would adjust a PR in the -Z direction the thickness of the material so as the stack got lower the robot would reach lower. This requires the PR to be "reset" after loading a new stack however and I would like to avoid this issue this time around.
My thinking is to somehow use the part present sensors on the tool to determine the position the robot needs to come down to. I set up a condition monitoring program to record the current position of the robot and populate a PR. But I cant have a motion group in the program called and I cant set PR(10)=LPOS without a motion group. Does anyone have a better way to do this or is what Im trying to do not possible?